This disclosure relates to a method for producing nanoparticles from a solid and to the nanoparticles produced therefrom. This disclosure also relates to composites that contain the nanoparticles produced therefrom.
In recent decades, nanoparticles have received an enormous amount of scientific attention due to their novel behavior and industrial applications, from quantum dots to catalysis. Synthesis of nanoparticles can be challenging, since they exist far from equilibrium with a high surface to volume ratio. Modern inorganic nanoparticles are generally produced by the decomposition of organic precursors, either by a sol-gel process or by pyrolysis. These methods have proven effective, but attainable nanoparticle chemistries are limited by the availability of appropriate precursors and corresponding decomposition reactions. A more chemically flexible nanoparticle production approach is mechanical attrition of a bulk material into small particles in a “top down” approach. Processing by rotary mills is the most common technique to form particles by attrition, but new techniques may be needed to produce new chemistries.
Engineered clusters of thermally or environmentally activated reactive micron-scale particles with fast reaction kinetics such a thermites have been shown to effectively produce nano-particles in a low-solubility matrix. However, the stability of reactive powders impedes implementation of this technology. To this end, cavitation erosion of a surface is investigated as a particle generation mechanism, along with a surface morphology-changing reaction that may change the mechanics of cavitation erosion.
Processes that suspend nanoparticles in solution can be advantageous from the prospective of safety and efficacy. Recent papers on particle safety indicate that nanoparticles can be highly hazardous to humans and persist in the environment. However, if particles are formed in an insoluble solution by an in-situ method, the airborne release of particles is minimized, lessening environmental contamination and respiratory distress, while concurrently hindering agglomeration. The addition of cavitation to this methodology can enhance in-situ particle formation. Cavitation can potentially enhance the wettability of particles, and the combination of cavitation and in-situ formation creates individual particles that are wetted to the melt, thus reducing tendency for agglomeration. However, the use of solvents (for the solution) necessitates the use of additional processing steps such as, for example, drying, in addition to disposing of the solvents.
It is desirable to find new methods to produce nanoparticles that do not have some of the aforementioned drawbacks.